my gmail on my macbook pro keep showing offline

I am trying to open my gmail on my Mac Pro but it shows my that its offline with a symbole that says account error. When I click on the symbole "account error" 3 options shows: Open connection doctor / Stay offline / Take all accounts online. It keep saying to verify my username and password to see if they are correct. And I know they are.

I am trying to open my gmail on my Mac Pro but it shows me that its offline with a symbole that says account error. When I click on the symbole "account error" 3 options shows: Open connection doctor / Stay offline / Take all accounts online. It keep saying to verify my username and password to see if they are correct. And I know they are. I want to the menu (on top of the page) and click on mailbox and scroll to "take all account on line" but nothing happen.